Raman spectroscopy is a powerful technique to identify the composition of materials. In

essence, it probes the spectrum of the characteristic mechanical vibrations of molecules by

focusing a laser beam on the material and detecting the optical frequency shifts induced by the

vibrating molecules. It has many applications ranging from the detection of counterfeiting to

the analysis of minerals on Mars, from monitoring chemical processes to probing processes in

living cells.

The key challenge of Raman spectroscopy is that the Raman signal is extremely weak and

therefore the equipment is bulky and expensive. Since the 1970’s it is known that the signal

can be boosted by orders of magnitude when the vibrating molecules are in close vicinity of

metal nanostructures, through a technique called surface enhanced Raman spectroscopy

(SERS). However, to make the technique viable there is a need for a low cost approach that

produces metal nanostructures on a substrate with nanometer accuracy in a very reproducible

manner.

In this project, we will explore an entirely new avenue that holds the promise to turn Raman

spectroscopy into a technique that can be incorporated in low-cost, compact devices. We will

use atomic layer deposition (ALD) to create metal nanostructures on silicon nitride waveguide

chips connected to optical fibers. As a proof-of-concept we will use this device to monitor the

chemical processes in an ALD-reactor itself, thereby taking full advantage of the compactness

of the device.